Non-caking solid particulate detergents



NON-CAKIN G SOLID PARTICULATE DETERGENTS Allen H. Lewis, Berkeley,.Calif., assignor to California Research Corporation, San :Francisco,Calif., a corporation of Delaware I No Drawing. Application August 1,1952 Serial No. 302,260

4 Claims. (Cl. 252138) This invention relates to improvements in solidpar compositions in current commercial use are marketedin the solidparticulate form as beads, flakes, chips, scales or granules, packagedinto containers such as metal drums, glass jars, wooden boxes andbarrels, paper and cloth bags, and cartons. Among these various. anionicsulfonate and sulfate synthetic detergent compositions, those having astheir effective detergent ingredients watersoluble salts of long-chainmono-alkyl benzene 'snlfonic acids and long-chain alkyl toluene sulfonicacids containing from 9 to 18 carbon atoms in the alkyl chain are knownto be eminently suitable-for the various purposes of industrial andhousehold use. Despite the fact that these alkyl benzene and alkyltoluene sulfonates are considered to be among the most satisfactory andefficient detergent compositions available in the trade,considerabledifiiculty is encountered in handling these. com positionsby the consumer because of the tendency of thesecompositions to cakeupon storage,'especially when exposed to warm and humid climaticconditions.

The occurrence of caking has been ascribed to a numher of factors: Ithas been said that it is caused by.-the

presence of the residual moisture in the dry detergent particles..Another explanation is that'caking is occa 'sioncd bythe penetration ofthe atmospheric moisture into the container even thoough it may appearto be .perfectly Well sealed. Theories have been oifered to relate thephenomenon of caking to the particular physical structure or chemicalnature of the detergent particles. Whatever be the, true cause or causesof caking,

its occurrence is: highly-undesirable. and annoying. It

interferes with the free flow of the particulate .d'etergentmaterialfrom the package; furthermore, lumpsof caked nited States Patentsiderably to the occurrence of caking in large containers, barrels andbags, particularly when heavy paper or cloth bags containing detergentare stacked or piled on top of each other. Even in the presence of verysmall amounts of moisture inthe surrounding atmosphere, the weight ofthe detergent material occasions undesirable caking and tackiness, whichmay become quite annoying at the packaging plant by clogging hoppers,and thus resulting in stoppages and waste of time.

.I have found that the caking tendency of sulfonate detergentcompositions can be markedly reduced and frequently completelyeliminated by incorporating in the detergent composition a smallquantity from about 2 to about 10% by weight, and preferably fromabout.-3 to about 5% by weight, of boric acid based on theentirecomposition. The detergent composition to which. the boric acid is addedcontains in each 100 partsby weight thereof from about 10 to about 95parts of the aforementioned sodium salts of long-chain mouoalkyl benzenesulfonic acids or long-chain monoalkyl toluene sulfonic acids, theremainder being inorganic sodium salt builders.

A convenient technique for producing solid particulate long-chainmonoalkyl aryl (benzene or toluene) sulfonate detergent compositions,which can bestabilized against caking in accordance with my invention,involves alkylating benzene or toluene with a long-chain olefin or anolefin polymer containing from 9 to 18 carbon atoms, for instance,polypropylene, employing a suitable efiectivealkylation catalyst such ashydrofluoric acid. The resulting long-chain (C to C monoalkyl benzene ortoluene product, and preferably thatiraction thereof which contains from12 to 15 carbon atoms in the long .alkyl'chain, is thereafter subjectedto sulfonationyvith are'converte'd to sodium salts by neutralizationwith an aqueous solution of caustic (NaOH) or sodium carbonate.Theprevailing practice isto leave all or a part of the unreactedsulfuric acid admixed with the sulfonic acids and to neutralize thesulfonic-sulfuric acid mixture to form an aqueous dispersion or slurryof the corresponding organic sodium monoalkyl.benzene or toluenesulfonate detergent and inorganic sodium sulfate builder.

i material'arefslow to disso1ve in fthe wash Water. While jpresjence ofmoisture: is fprobabl'y the chief factor reflsponsible for theoccurrencejot cakingjin sulfonate deterg cnt compositions, Qariotherimportant concurring "fac! tot-is the "pressure exerted by the weight ofthe mass of detergent material in the package. It contributescon-Another technique for preparing detergent sodium monoallcyl benzeneortoluene sulfonates, improved or stabilized against caking inaccordance with my, invention, involves condensation of benzene withchlorinated C to C acycliohydrocarbons such asarefconta'ined' in achlorinated kerosene fraction of petroleum, in the presence of asuitable catalyst, fdrdinarilyjAlCl; The resulting miizture of C to C.monoall y1 benzenes for tolaenes is then sulfonated and neutralized ina jc'onyentionai manner, and thefinal slurry of 'monoalkyl benzene ortoluene sulfonate and sodium sulfate'is .dried'and reduced to thedesired particle form and size. Frequent- 1y, additional amounts ofbuilders, e g, more'sodium sulfate and other inorganic sodiumls'alts,such assodiuin silicate-and particularly phosphates such as tetrasodiumpyrophosphate or sodium tripolyphosphate, may be added to theneutralized sulfonate slurry before drying this latter in accordancewith the specifications for the ultimately desired detergentcomposition. The slurry built with these various sodium salts isconverted to the desired solid form and particle size by an appropriatedry ing technique, for instance, by spray-drying or drumdrying.

In addition to the inorganic sodium salt builders, organic builders, inparticular sodium carboxymethyl cellulose, may be added to theneutralized sulfonate slurry in order to improve its detergencycharacteristics.

The introduction of the caking preventive of my invention, boric acid,usually in its conventional form of crystalline flakes, into thedetergent composition is preferably carried out by adding boric acid,sodium borate, or borax to the neutralizing solution of sodium hydroxideor sodium carbonate, which is then employed to neutralize the sulfonicacid mixture. The pH of the neutralized sulfonate slurry should be lessthan about pH=8.3 and may be as low as pH=6.0, but preferably from aboutpH=7.0 to about pH=8.0, in order that boric acid rather than boric acidsalts be present in the final product. One may also introduce boric acidby dispersing it in the sulfonic acid mixture.

Generally, sodium salt builders and extenders, such as sodium sulfate,tetrasodium pyrophosphate, sodium polyphosphates, sodium silicates,sodium chloride, sodium carbonate, sodium carboxymethyl cellulose, donot interfere with the anti-caking effect of boric acid provided theyare employed in proportions which do not occasion a too high pH of theneutralized sulfonate slurry.

If it is desired to utilize the anti-caking effect of boric acid in themanufacture of the so-called heavy-duty detergent compositions, whichgenerally contain alkaline sodium salt builders giving to thesecompositions a final pH greater than about 8.3 and as high as 11.5, whenused in aqueous solutions of 0.2% to 0.5% in concentrationconventionally employed in the laundry practice and in houshold washing,this may be accomplished by carrying out the compounding of thedetergent composition in two separate stages. The alkaline builderswhich would otherwise nullify the anti-caking effect because of theiralkalinity are withheld, while the other ingredients of the detergentcomposition including the boric acid, are dried from an essentiallyneutral slurry formed as described hereinabovel In this way a solid,particulate, non-caking detergent intermediate composition is prepared,which can be readily handled in manufacturing equipment without tendencyto stick or cake, and which can then be compounded with more alkalinebuilders, such as sodium tripolyphosphate or sodium carbonate, byblending the dry materials or by the use of a process such as isdescribed in British Patent No. 584,698.

The degree of improvement in the caking characteristics obtained foreach particular composition may be varied somewhat depending on theexact amount of boric acid added, the method of drying the slurry(drum-drying or spray-drying), and the proportion of the activesulfonate detergent in the slurry. A definite advantage secured by theintroduction of boric acid resides in a higher moisture content whichcan be tolerated in the sulfonate detergent composition without the riskof excessive caking technique. have been carried out.

The first series of; tests (humiditycabinet tests) was eifected asfollows: After incorporating boric acid into the detergent compositionin accordance with the procedures described hereinabove, the neutralizedslurry was dried to yield the desired particle form product. Weighedsamples of the dried particulate compositions, screened through a No. 16sieve and collected on a No. 200 sieve, were placed in small untreatedsealed cardboard boxes (1%" x 2 /2" x 4"), and three samples of thedetergent composition containing boric acid together with three samplescontaining no boric acid were placed in a completely random manner in ahumidity cabinet, exposed to a relative humidity of about at atemperature of about F. After the exposure period of seven days, theboxes containing samples were re-weighed, and the extent of caking wasdetermined by cutting away an entire side of the cardboard box andcarefully transferring its contents onto a No. 4 sieve 4" mesh) from aminimum height. Thesieve was then gently swirled until all particlescame into contact with the screen. The material which did not passthrough the screen by this treatment was considered to be caked, and itsweight vs. the weight of the original sample was designated thepercentage of material caked. The following Table I contains the resultsof several of these tests carried out in the humidity cabinet.

TABLE I Eflect of boric acid as a caking-preventive as shown b humiditycabinet tests Boric Acid in percent Detergent Composi- Test tlon in eachparts 7 N o. by weight Percent Cnked b y (Averweight age) Remarksmonalkyl Co01a 0 G5 benzene.

60 parts Na2SO4..

40 parts sodium 2 monoalkyl Cn-Cia {40 parts sodium Boric acid intro- 316 duced into benzene.

60 parts M12804..- izing solution.

NaOH neutral- 40 parts sodium 3 monoa1l ylCgG1s 5 5 Do.

benzene. 60 parts Na2SO4 40 parts sodium 4..' mouoalkylCa-Ol benzene. 60parts NazSO. {to parts monoalkyl (Cu-C15) toluene sulfonate. oil-partsNazS04 The second seriesof tests (pressure-caking tests) were carried.out as follows: Neutralized slurries of similarlyprepared long-chain C-C monalkyl benzene and toluene sulfonate detergent compositionscontaining from 2 to 10% by weight of boric acid were dried and reducedto the desired form and size. The dried compositions were screenedthrough a No. 12 sieve and collected on a No. 200 sieve, and 50 gramsamples were placed into brass cylinders, 2" in diameter and 3-4" high,closed by a push piston at the top. A weight which varied from 2 to 4kilograms was applied to the piston for 5 minutes. Then the contents ofthe brass cylinder were pushed out. The cylinder-shape sample wasdropped from a height of 1 foot onto a No. 4 screen. The ratio of theweight of the material remaining on the screen to the weight of theoriginal sample was taken to indicate the percentage of material.eakedft TABLE II Efiect of boric acid as a caking-preventive as shownby pressure-caking rem 1 Added as borer to the neutralizing solution ofN aOH.

As can be seen from the data in Tables I and II, a remarkable reductionof the caking tendency is obtained by the addition of boric acid to thesulfonate detergent compositions in accordance with my invention. In anumber of tests this tendency practically disappeared in the presence ofboric acid. Particularly striking is the reduction of caking andtackiness in samples of long chain C -C monoalkyl toluene sulfonatesheretofore considered exceptionally susceptible to caking.

The sulfonate detergent compositions, capable of being stabilizedagainst caking by the addition of boric acid in accordance with myinvention, may also contain minor amounts of additives to improve odor,sudsing, suds stability and other characteristics thereof, such asperfumes, fatty alcohols, fatty acid alkanolamides, etc. The phraseconsisting essentially as employed in the appended claims is intended toindicate the essential components of the detergent composition claimed,but does not preclude the presence of these additives.

I claim:

1. A built detergent composition in the form of small solid particlesconsisting essentially of about to about 95 parts by weight of a sodiumsalt of an alkyl aryl sul fonic acid selected from the group of alkylbenzene sulfonic and alkyl toluene sulfonic acids containing from 9 to18 carbon atoms in the alkyl chain, sodium salt detergent builders in anamount sufiicient to bring the aggregate weight of the sulfonic acidsalt and the detergent builders to 100 parts by weight and so selectedfrom the group consisting of sodium sulfate, sodium polyphosphates,sodium silicates, sodium chloride, sodium carbonate and sodiumcarboxymethyl cellulose that the pH of the built detergent compositionis less than about 8.3, and from about 2 to about 10% by weight, basedon the aggregate weight of the sulfonic acid salt and the detergentbuilders, of boric acid uniformly dispersed in each particle of thedetergent composition.

2. A built detergent composition as defined in claim 1, wherein boricacid is present in an amount from about 3 to about 5% by weight, basedon the aggregate weight of the sulfonic acid salt and the detergentbuilders.

3. A built detergent composition in the form of small solid particlesconsisting essentially of about 10 to about 95 parts by weight of asodium salt of an alkyl aryl sulfonic acid selected from the group ofalkyl benzene sulionic and alkyl toluene sulfonic acids containing from9 to 18 carbon atoms in the alkyl chain, sodium salt detergent builders,in an amount sufiicient to bring the aggregate weight of the sulfonicacid salt and the detergent builders to 100 parts by weight and soselected from the group consisting of sodium sulfate, sodiumpolyphosphates, sodium silicates, sodium chloride, sodium carbonate andsodium carboxymethyl cellulose that the pH of the built detergentcomposition is in the range from about 7.0 to about 8.0, and from about2 to about 10% by weight, based on the aggregate weight of the sulfonicacid salt and the detergent builders, of boric acid uniformly dispersedin each particle of the detergent composition.

4. In the preparation of a solid, particulate detergent composition, inwhich the organic detergent component is a sodium salt of an alkyl arylsulfonic acid from the group consisting of C -C alkyl benzene sulfonicand C -C alkyl toluene sulfonic acids and the inorganic components aresodium salt detergent builders, said detergent composition beingproduced by sulfonating a mixture of alkyl aryl hydrocarbons from thegroup of C to C alkyl benzenes and C to C alkyl toluenes, neutralizingthe resulting sulfonation product mixture and drying said mixture tosolid detergent particles, a method permitting of reducing the cakingtendency of said detergent composition, which comprises introducing fromabout 2 to about 10% of boric acid, based on the weight of the final drydetergent composition, into the neutralizing solution for thesulfonation product mixture, neutralizing said sulfonation mixture to apH of less than about 8.3, drying the neutralized mixture to smallparticle size and compounding the resulting dn'ed particles resistant tocaking with sodium salt detergent builders capable of imparting a pHfrom about 8.3 to about 11.5 to an aqueous solution of the resultingblend, ranging from 0.2% to 0.5% in concentration.

References Cited in the file of this patent UNITED STATES PATENTS2,119,970 Smith June 7, 1938 2,480,579 Holuba Aug. 30, 1949 2,541,248Hibbs Feb. 13, 1951 2,579,380 Funderburl: 18, 1951

1. A BUILT DETERGENT COMPOSITION IN THE FORM OF SMALL SOLID PARTICLESCONSISTING ESSENTIALLY OF ABOUT 10 TO ABOUT 95 PARTS BY WEIGHT OF ASODIUM SALT OF AN ALKYL ARYL SULFONIC ACID SELECTED FROM THE GROUP OFALKYL BENZENE SULFONIC AND ALKYL TOLUENE SULFONIC ACIDS CONTAINING FROM9 TO 18 CARBON ATOMS IN THE ALKYL CHAIN, SODIUM SALT DETERGENT BUILDERSIN AN AMOUNT SUFFICIENT TO BRING THE AGGREGATE WEIGHT OF THE SULFONICACID SALT AND THE DETERGENT BUILDERS TO 100 PARTS BY WEIGHT AND SOSELECTED FROM THE GROUP CONSISTING OF SODIUM SULFATE, SODIUMPOLYPHOSPHATES, SODIUM SILICATES, SODIUM CHLORIDE, SODIUM CARBONATE ANDSODIUM CARBOXYMETHYL CELLULOSE THAT THE PH OF THE BUILT DETERGENTCOMPOSITION IS LESS THAN ABOUT 8.3, AND FROM ABOUT 2 TO ABOUT 10% BYWEIGHT, BASED ON THE AGGREGATE WEIGHT OF THE SULFONIC ACID SALT AND THEDETERGENT BUILDERS, OF BORIC ACID UNIFORMLY DISPERSED IN EACH PARTICLEOF THE DETERGENT COMPOSITION.